Ensure you are first of all registered for Digimap – http://digimap.edina.ac.uk/ then choose Ordnance Survey – Roam service.
You can search for a location in Roam using a place name, road name, postcode, grid reference, easting/northing or latitude/longitude Then you can zoom in/out and drag the map around so that you’ve got the area you want on your map in the middle of the screen.
Then press the Print button within the service to generate a map file. By default the map file will be created as a PDF but you can change the format to PNG or JPG (which would be easier if you need to insert the map image into a Word/PowerPoint document).
Take a look at the help pages – http://digimap.edina.ac.uk/webhelp/os/getting_started/i_just_want_a_map.htm